docs: def _build_variant_label(
              build, chromosome, position, reference_allele, variant_allele,
              gene_symbols=None
      ):
          """
          Function to build HGVS variant labels
          :param build: {str} build id
          :param chromosome: {str} chromosome
          :param position: {str} variation position as string or int
          :param reference_allele: {str} single letter ref bp
          :param variant_allele: {str} single letter bp change
          :param gene_symbol: {str} gene symbol (hgvs)
          :return: {str} variant label
          """
          variant_label = ''
          prefix = ''
          if gene_symbols and len(gene_symbols) == 1 and gene_symbols[0]:
              prefix = "{0}{1}({2})".format(build, chromosome, gene_symbols[0])
          else:
              prefix = "{0}{1}".format(build, chromosome)
          if reference_allele == '-':
              variant_label = "{0}:g.{1}ins{2}".format(prefix, position, variant_allele)
          elif variant_allele == '-':
              variant_label = "{0}:g.{1}del{2}".format(
                  prefix, position, reference_allele)
          else:
              variant_label = "{0}:g.{1}{2}>{3}".format(
                  prefix, position, reference_allele, variant_allele)
          return variant_label